ABSTRACT
Experimentsontheadsorptionkinetics(variationwithtimeoftheweightof adsorbedwaterpergramofsilicaatconstantrelativehumidity,RH)showedthat theamountofwatervaportakenupbyfumedsilicaincreasedwithincreasing adsorptiontime[80].Theprocessofwateruptakecanbedividedintotwostages. Duringthefirststagetheadsorptionproceededmoreintensivelyandadsorbed weightincreasedveryfast.Duringthesecondstagetheadsorptionprocesswas muchslowerandtheadsorbedamounttendedtoreachitssaturationweight. Thetimeneededtoreachthesaturationadsorptionstronglydependedonthe RHandwassmallerforthesmallerone.AtlargeRH,duringthesecondstage theadsorbedweightstillincreasedappreciably,whereasatlowRHitwasconstant.
